Fire-suppression systems are installed in virtually all new buildings to help protect property and persons occupying such buildings in the case of fire. Fire-suppression systems have an array of fire sprinklers strategically located throughout a building. Water flows from a main conduit and through branch conduits and sprinkler heads when the fire-suppression system operates. Sprinkler heads often include a "plug" made from a material having a relatively low melting point that prevents water from flowing through the sprinkler heads when the fire-suppression system is not in operation. The low-melting point material melts when exposed to high temperatures, thereby allowing water to flow onto the fire through the sprinkler heads.
There are several types of fire-suppression systems, including both "wet" and "dry" systems. A "wet" system has water in the main and branch conduits. A "dry" system, on the other hand, has pressurized air in the branch conduits leading to the sprinkler heads. The pressurized air forces a clapper mounted in the main conduit to remain in a closed position, thereby preventing water from flowing into the branch conduits. The pressurized air is released when the sprinkler heads open in response to fire. This causes the clapper to open, and water then flows out of the sprinkler heads.
Fire-suppression systems typically include at least one shut-off valve coupled to the main conduit for interrupting the flow of water to the building when repair work or safety inspections are required. The shut-off valve may be located on the inside or outside of the building. Common outdoor valves include wall-post-indicator valves (WPIV) and post-indicator valves (PIV). WPIVs are mounted to outside walls of buildings and include control wheels that are rotated to open and close the valve. PIVs are located away from the building, typically near an adjacent street, and look similar to fire hydrants. PIVs usually have a rotatable nut that is rotated to open and close the valve. Other types of valves, such as outside stem-and-yoke valves (OS&Y) and butterfly valves, also commonly are used with fire-suppression systems.
Fire-suppression systems also generally include control panels that receive signals from various sensors located throughout the building. Flow, pressure and tamper sensors are examples of sensors coupled to fire-suppression systems. The sensors indicate whether an alarm condition exists as a result of fire, or that maintenance is required. Flow sensors are mounted to main or branch conduits to signal the control panel when water is flowing through the system. Low and/or high pressure sensors are coupled to main air-or water-carrying conduits to detect if the fluid pressure within such conduits drops below or rises above an acceptable, predetermined level. This most likely occurs as a result of a fire or loss of electrical power to the air compressor. Tamper sensors are mounted on shut-off valves (e.g., WPIVs, PIVs and OS&Ys) to signal the control panel if the valve is turned off during a maintenance inspection or by unauthorized persons tampering with the valves.
When a sensor is activated, a signal from the sensor activates an alarm on the control panel. The control panel contacts a monitoring service by modem. The monitoring service can then determine what caused the alarm and take the appropriate corrective action. For example, the monitoring service may contact the local fire department, maintenance personnel for the fire-suppression system or maintenance personnel for the building.
Maintenance personnel also periodically test fire-suppression systems, including the sensors, to ensure that the system and sensors are operating properly. For example, a drain valve can be opened to run water through a conduit to which a flow sensor is coupled to activate the sensor.
A primary problem encountered by maintenance personnel is that there is no way to determine if a sensor is working properly simply by observing the sensor. Instead, the person testing the system must walk to the control panel to check whether an alarm is activated on the panel in response to activation of the sensor being observed. The control panel almost certainly is located at a remote location, and may be hundreds of yards away from the sensor being observed. With reference to flow sensors, the maintenance person (1) walks back to the drain valve and shuts it off, thereby deactivating the flow sensor, and (2) then returns to the control panel to ensure that the control panel alarm deactivated upon deactivation of the sensor. Each sensor, including all flow, pressure and tamper sensors, is similarly tested.
As a result, testing fire-suppression systems is a laborious, time-consuming task that requires walking back and forth several times from each sensor to the control panel to ensure proper sensor operation. It often is faster to have maintenance personnel work in tandem with one person activating the sensor while a second person monitors the control panel to check that it operates properly. However, employing an extra person increases the cost of testing fire-suppression systems.
The Notifier Company (Notifier) has designed a device to make testing fire-suppression systems more efficient. The NOTIFIER devices have a light-emitting diode (LED) coupled to a sensor through a coaxial cable. The LED is positioned in a metal or plastic box mounted to a wall near the sensor. The LED blinks when the sensor is inactive and is steady when the sensor is active. The NOTIFIER device still requires that maintenance personnel walk to the control panel when the sensor is coupled to a WPIV or PIV positioned outside of the building. Moreover, Notifier's wall-mounted units, coaxial coupling cables and cable conduits are expensive, especially because one conduit and box are used per sensor and large buildings have many sensors. Notifier's wall-mounted LEDs also apparently are not water-resistant, which prevents using them outdoors on WPIVs or PIVs.
It should be apparent from the foregoing that alarms for testing and monitoring sensor operation, particularly sensors used for fire-suppression systems, are still required by the industry.